/*************************************************************************/
/*  dvector.h                                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
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/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
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/* distribute, sublicense, and/or sell copies of the Software, and to    */
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/* the following conditions:                                             */
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/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
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/*************************************************************************/
#ifndef DVECTOR_H
#define DVECTOR_H

#include "os/memory.h"
#include "os/copymem.h"
#include "pool_allocator.h"
#include "safe_refcount.h"
#include "os/rw_lock.h"

struct MemoryPool {

	//avoid accessing these directly, must be public for template access

	static PoolAllocator *memory_pool;
	static uint8_t *pool_memory;
	static size_t *pool_size;


	struct Alloc {

		SafeRefCount refcount;
		uint32_t lock;
		void *mem;
		PoolAllocator::ID pool_id;
		size_t size;

		Alloc *free_list;

		Alloc() { mem=NULL; lock=0; pool_id=POOL_ALLOCATOR_INVALID_ID; size=0; free_list=NULL; }
	};


	static Alloc *allocs;
	static Alloc *free_list;
	static uint32_t alloc_count;
	static uint32_t allocs_used;
	static Mutex *alloc_mutex;
	static size_t total_memory;
	static size_t max_memory;


	static void setup(uint32_t p_max_allocs=(1<<16));
	static void cleanup();
};


/**
	@author Juan Linietsky <reduzio@gmail.com>
*/


template<class T>
class PoolVector {

	MemoryPool::Alloc *alloc;


	void _copy_on_write() {


		if (!alloc)
			return;

		ERR_FAIL_COND(alloc->lock>0);

		if (alloc->refcount.get()==1)
			return; //nothing to do


		//must allocate something

		MemoryPool::alloc_mutex->lock();
		if (MemoryPool::allocs_used==MemoryPool::alloc_count) {
			MemoryPool::alloc_mutex->unlock();
			ERR_EXPLAINC("All memory pool allocations are in use, can't COW.");
			ERR_FAIL();
		}

		MemoryPool::Alloc *old_alloc = alloc;

		//take one from the free list
		alloc = MemoryPool::free_list;
		MemoryPool::free_list = alloc->free_list;
		//increment the used counter
		MemoryPool::allocs_used++;

		//copy the alloc data
		alloc->size=old_alloc->size;
		alloc->refcount.init();
		alloc->pool_id=POOL_ALLOCATOR_INVALID_ID;
		alloc->lock=0;

#ifdef DEBUG_ENABLED
		MemoryPool::total_memory+=alloc->size;
		if (MemoryPool::total_memory>MemoryPool::max_memory) {
			MemoryPool::max_memory=MemoryPool::total_memory;
		}
#endif

		MemoryPool::alloc_mutex->unlock();


		if (MemoryPool::memory_pool) {


		} else {
			alloc->mem = memalloc( alloc->size );
		}

		{
			Write w;
			w._ref(alloc);
			Read r;
			r._ref(old_alloc);

			int cur_elements = alloc->size/sizeof(T);
			T*dst = (T*)w.ptr();
			const T*src = (const T*)r.ptr();
			for(int i=0;i<cur_elements;i++) {
				memnew_placement(&dst[i],T(src[i]));
			}
		}


		if (old_alloc->refcount.unref()==true) {
			//this should never happen but..

#ifdef DEBUG_ENABLED
			MemoryPool::alloc_mutex->lock();
			MemoryPool::total_memory-=old_alloc->size;
			MemoryPool::alloc_mutex->unlock();
#endif

			{
				Write w;
				w._ref(old_alloc);

				int cur_elements = old_alloc->size/sizeof(T);
				T*elems = (T*)w.ptr();
				for(int i=0;i<cur_elements;i++) {
					elems[i].~T();
				}

			}

			if (MemoryPool::memory_pool) {
				//resize memory pool
				//if none, create
				//if some resize
			} else {


				memfree( old_alloc->mem );
				old_alloc->mem=NULL;
				old_alloc->size=0;


				MemoryPool::alloc_mutex->lock();
				old_alloc->free_list=MemoryPool::free_list;
				MemoryPool::free_list=old_alloc;
				MemoryPool::allocs_used--;
				MemoryPool::alloc_mutex->unlock();
			}

		}

	}

	void _reference( const PoolVector& p_dvector ) {

		if (alloc==p_dvector.alloc)
			return;

		_unreference();

		if (!p_dvector.alloc) {
			return;
		}

		if (p_dvector.alloc->refcount.ref()) {
			alloc=p_dvector.alloc;
		}

	}


	void _unreference() {

		if (!alloc)
			return;

		if (alloc->refcount.unref()==false) {
			alloc=NULL;
			return;
		}

		//must be disposed!

		{
			int cur_elements = alloc->size/sizeof(T);
			Write w = write();

			for (int i=0;i<cur_elements;i++) {

				w[i].~T();
			}

		}

#ifdef DEBUG_ENABLED
		MemoryPool::alloc_mutex->lock();
		MemoryPool::total_memory-=alloc->size;
		MemoryPool::alloc_mutex->unlock();
#endif


		if (MemoryPool::memory_pool) {
			//resize memory pool
			//if none, create
			//if some resize
		} else {

			memfree( alloc->mem );
			alloc->mem=NULL;
			alloc->size=0;


			MemoryPool::alloc_mutex->lock();
			alloc->free_list=MemoryPool::free_list;
			MemoryPool::free_list=alloc;
			MemoryPool::allocs_used--;
			MemoryPool::alloc_mutex->unlock();

		}

		alloc=NULL;
	}

public:

	class Access {
	friend class PoolVector;
	protected:
		MemoryPool::Alloc *alloc;
		T * mem;

		_FORCE_INLINE_ void _ref(MemoryPool::Alloc *p_alloc) {
			alloc=p_alloc;
			if (alloc) {
				if (atomic_increment(&alloc->lock)==1) {
					if (MemoryPool::memory_pool) {
						//lock it and get mem
					}
				}

				mem = (T*)alloc->mem;
			}
		}

		_FORCE_INLINE_ void _unref() {


			if (alloc) {
				if (atomic_decrement(&alloc->lock)==0) {
					if (MemoryPool::memory_pool) {
						//put mem back
					}
				}

				mem = NULL;
				alloc=NULL;
			}


		}

		Access() {
			alloc=NULL;
			mem=NULL;
		}


	public:
		virtual ~Access() {
			_unref();
		}
	};

	class Read : public Access {
	public:

		_FORCE_INLINE_ const T& operator[](int p_index) const { return this->mem[p_index]; }
		_FORCE_INLINE_ const T *ptr() const { return this->mem; }

		void operator=(const Read& p_read) {
			if (this->alloc==p_read.alloc)
				return;
			this->_unref();
			this->_ref(p_read.alloc);
		}

		Read(const Read& p_read) {
			this->_ref(p_read.alloc);
		}

		Read() {}


	};

	class Write : public Access {
	public:

		_FORCE_INLINE_ T& operator[](int p_index) const { return this->mem[p_index]; }
		_FORCE_INLINE_ T *ptr() const { return this->mem; }

		void operator=(const Write& p_read) {
			if (this->alloc==p_read.alloc)
				return;
			this->_unref();
			this->_ref(p_read.alloc);
		}

		Write(const Write& p_read) {
			this->_ref(p_read.alloc);
		}

		Write() {}

	};


	Read read() const {

		Read r;
		if (alloc) {
			r._ref(alloc);
		}
		return r;

	}
	Write write() {

		Write w;
		if (alloc) {
			_copy_on_write(); //make sure there is only one being acessed
			w._ref(alloc);
		}
		return w;
	}

	template<class MC>
	void fill_with(const MC& p_mc) {


		int c=p_mc.size();
		resize(c);
		Write w=write();
		int idx=0;
		for(const typename MC::Element *E=p_mc.front();E;E=E->next()) {

			w[idx++]=E->get();
		}
	}


	void remove(int p_index) {

		int s = size();
		ERR_FAIL_INDEX(p_index, s);
		Write w = write();
		for (int i=p_index; i<s-1; i++) {

			w[i]=w[i+1];
		};
		w = Write();
		resize(s-1);
	}

	inline int size() const;
	T get(int p_index) const;
	void set(int p_index, const T& p_val);
	void push_back(const T& p_val);
	void append(const T& p_val) { push_back(p_val); }
	void append_array(const PoolVector<T>& p_arr) {
		int ds = p_arr.size();
		if (ds==0)
			return;
		int bs = size();
		resize( bs + ds);
		Write w = write();
		Read r = p_arr.read();
		for(int i=0;i<ds;i++)
			w[bs+i]=r[i];
	}

	PoolVector<T> subarray(int p_from, int p_to) {

		if (p_from<0) {
			p_from=size()+p_from;
		}
		if (p_to<0) {
			p_to=size()+p_to;
		}
		if (p_from<0 || p_from>=size()) {
			PoolVector<T>& aux=*((PoolVector<T>*)0); // nullreturn
			ERR_FAIL_COND_V(p_from<0 || p_from>=size(),aux)
		}
		if (p_to<0 || p_to>=size()) {
			PoolVector<T>& aux=*((PoolVector<T>*)0); // nullreturn
			ERR_FAIL_COND_V(p_to<0 || p_to>=size(),aux)
		}

		PoolVector<T> slice;
		int span=1 + p_to - p_from;
		slice.resize(span);
		Read r = read();
		Write w = slice.write();
		for (int i=0; i<span; ++i) {
			w[i] = r[p_from+i];
		}

		return slice;
	}

	Error insert(int p_pos,const T& p_val) {

		int s=size();
		ERR_FAIL_INDEX_V(p_pos,s+1,ERR_INVALID_PARAMETER);
		resize(s+1);
		{
			Write w = write();
			for (int i=s;i>p_pos;i--)
				w[i]=w[i-1];
			w[p_pos]=p_val;
		}

		return OK;
	}


	bool is_locked() const { return alloc && alloc->lock>0; }

	inline const T operator[](int p_index) const;

	Error resize(int p_size);

	void invert();

	void operator=(const PoolVector& p_dvector) { _reference(p_dvector); }
	PoolVector() { alloc=NULL; }
	PoolVector(const PoolVector& p_dvector) { alloc=NULL; _reference(p_dvector); }
	~PoolVector() { _unreference(); }

};

template<class T>
int PoolVector<T>::size() const {

	return alloc ? alloc->size/sizeof(T) : 0;
}

template<class T>
T PoolVector<T>::get(int p_index) const {

	return operator[](p_index);
}

template<class T>
void PoolVector<T>::set(int p_index, const T& p_val) {

	if (p_index<0 || p_index>=size()) {
		ERR_FAIL_COND(p_index<0 || p_index>=size());
	}

	Write w = write();
	w[p_index]=p_val;
}

template<class T>
void PoolVector<T>::push_back(const T& p_val) {

	resize( size() + 1 );
	set( size() -1, p_val );
}

template<class T>
const T PoolVector<T>::operator[](int p_index) const {

	if (p_index<0 || p_index>=size()) {
		T& aux=*((T*)0); //nullreturn
		ERR_FAIL_COND_V(p_index<0 || p_index>=size(),aux);
	}

	Read r = read();

	return r[p_index];
}


template<class T>
Error PoolVector<T>::resize(int p_size) {


	if (alloc==NULL) {

		if (p_size==0)
			return OK; //nothing to do here

		//must allocate something
		MemoryPool::alloc_mutex->lock();
		if (MemoryPool::allocs_used==MemoryPool::alloc_count) {
			MemoryPool::alloc_mutex->unlock();
			ERR_EXPLAINC("All memory pool allocations are in use.");
			ERR_FAIL_V(ERR_OUT_OF_MEMORY);
		}

		//take one from the free list
		alloc = MemoryPool::free_list;
		MemoryPool::free_list = alloc->free_list;
		//increment the used counter
		MemoryPool::allocs_used++;

		//cleanup the alloc
		alloc->size=0;
		alloc->refcount.init();
		alloc->pool_id=POOL_ALLOCATOR_INVALID_ID;
		MemoryPool::alloc_mutex->unlock();

	} else {

		ERR_FAIL_COND_V( alloc->lock>0, ERR_LOCKED ); //can't resize if locked!
	}

	size_t new_size = sizeof(T)*p_size;

	if (alloc->size==new_size)
		return OK; //nothing to do

	if (p_size == 0 ) {
		_unreference();
		return OK;
	}

	_copy_on_write(); // make it unique

#ifdef DEBUG_ENABLED
	MemoryPool::alloc_mutex->lock();
	MemoryPool::total_memory-=alloc->size;
	MemoryPool::total_memory+=new_size;
	if (MemoryPool::total_memory>MemoryPool::max_memory) {
		MemoryPool::max_memory=MemoryPool::total_memory;
	}
	MemoryPool::alloc_mutex->unlock();
#endif


	int cur_elements = alloc->size / sizeof(T);

	if (p_size > cur_elements ) {

		if (MemoryPool::memory_pool) {
			//resize memory pool
			//if none, create
			//if some resize
		} else {

			if (alloc->size==0) {
				alloc->mem = memalloc( new_size );
			} else {
				alloc->mem = memrealloc( alloc->mem, new_size );
			}
		}

		alloc->size=new_size;

		Write w = write();

		for (int i=cur_elements;i<p_size;i++) {

			memnew_placement(&w[i], T );
		}


	} else {

		{
			Write w = write();
			for (int i=p_size;i<cur_elements;i++) {

				w[i].~T();
			}

		}

		if (MemoryPool::memory_pool) {
			//resize memory pool
			//if none, create
			//if some resize
		} else {

			if (new_size==0) {
				memfree( alloc->mem );
				alloc->mem=NULL;
				alloc->size=0;

				MemoryPool::alloc_mutex->lock();
				alloc->free_list=MemoryPool::free_list;
				MemoryPool::free_list=alloc;
				MemoryPool::allocs_used--;
				MemoryPool::alloc_mutex->unlock();

			} else {
				alloc->mem = memrealloc( alloc->mem, new_size );
				alloc->size=new_size;
			}
		}

	}

	return OK;
}

template<class T>
void PoolVector<T>::invert() {
	T temp;
	Write w = write();
	int s = size();
	int half_s = s/2;

	for(int i=0;i<half_s;i++) {
		temp = w[i];
		w[i] = w[s-i-1];
		w[s-i-1] = temp;
	}
}

#endif
